Emergency control for centralized traffic control systems



Oct. 20, 1953 H. c. VAN TAssEL EMERGENCY CONTROL FOR CENTRALIZED TRAFFIC CONTROL SYSTEMS Filed Oct. 28. 1949 INVENTOR.

y? Tassel.

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m w .I n i@ s A .SNS @s RQ@ a typical field station of a centralized traffic control system is shown, corresponding to the lefthand end of a passing siding on a single track railroad, together with circuits and apparatus embodying-my invention arranged to control a track switch and the signals which govern traic movements over the switch in the right to left direction, and in diagrammatic form, the communication apparatus by means of which the switch and signals are manually controllable from a central oiice. To simplify the circuits, the local sources of current for energizing the various relays are identified by their terminals which are designated B and N, respectively.

The communication system `by which the manual control of the switches kand signals is effected is to be understood to be a modification of that shown in Letters Patent of the United States, No. 2,411,375, issued November 19, 1946. to Arthur P. J ackel for Remote Control Systems.

The communication system comprises a plurality of control levers and starting buttons associated with coding units at the control oiiice, and corresponding coding units at eld stations of which but one of each is shown, as indicated by the legends Ofce Coding Unit and Station Coding Unit. The oiiice and station coding units are connected by a normally energized circuit including the line wires Y and Z extending from the ofce to each station. A line relay such as the relay iR, is connected across the line wires Y and Z at each station, and is normally held energized by current from the battery B9 located at the office. The communication system is normally inactive, but may be set into operation to transmit a control code to a particular station by pressing a starting button such as the button ISTB identifying the desired station. Each control code vcomprises a series of code elements formed by opening and closing the line circuit by the operation of a transmitter relay T. Each control code includes a group of selecting elements, which operates a delivery relay such as relay ID at the selected station only, with the same effect as if this relay were energized directly over a contact of the starting button and a wire I6 as indicated diagrammatically in the drawing. Relay ID when energized prepares circuits over which a series of polar stick control relays are operated to normal or reverse in accordance with the positions of their control levers at the oliice, in accordance with the character of a second group of elements in the control code. The code responsive control relays at the station include a switch control relay IWS and a signal control relay 2LHS. Relay IWS is Ioperable to normal or reverse by impulses supplied over wires 9 and II, in accordance with the position of a switch lever ISV?, and governs the switch machine IWM for the track switch IW. Relay ZLHS is controlled over wires I3 and 8i and governs the clearing of the entering signals ZLA and 2LB`, for the single track block extending to the left, in accordance with the position of a signal control lever ',iSG. The switch machine IWM is of the usual dual control type, normally operable by power in accordance with the position of relay IWS, and also operable by a hand-throw lever, not shown. The track switch IlW and its control relays IWS jointly control a normal and a reverse switch indication relay INWP and IRWP, contacts of which serve to select signal 2LA or 2LB for clearing in accordance with the direction selected by relay ZLHS and the route established by switch IW.

Although only signals and associated circuits for traino movements from right to left are shown and described, it will be understood that tramo movements from left to right may be governed in a similar manner by a provision of a second signal control relay and associated circuits for the control of signal 2R.

It is also to be understood that the communication system includes apparatus for transmitting indication codes for reporting the passage of trains and for indicating the positions of .the switches and the condition of the signals, not shown herein.

The main track and the passing siding are equipped with conventional direct current track circuits. The detector section IT is equipped with a track circuit including the battery ITB and detector relay ITR. The main line portion of the passing siding, section 2LT, and the passing track section QLBT, are each equipped with a track circuit, including a battery, ZLTB or 2LBTB, and a series approach relay, 2LAR or 2LBAR, in addition to the usual track relay at their distant end, not shown. These circuits are adjusted so that the approach relay picks up when a train approaches Within a predetermined distance of the battery end of the circuit to thereby indicate the approach of a train. It is to be understood that my invention is not limited to use with conventional direct current track circuits lof the type shown and described, but may be employed with signaling systems incorporating other types of track circuits, such as coded track circuits, for example.

The apparatus added to the centralized traic control system in accordance with my invention comprises a group of relays and a manually operable switch at each of the eld stations and as shown for the single eld station in the drawing these comprise an emergency relay IER, a manually controlled switch control relay iKOC, and a manually operable switch control lever IKO. The emergency relay IER is provided with a pick-up circuit including a back contact d of a station disconnect relay IRPP controlled by the communication system, and front contact g of an approach locking relay ZLAS associated with the signals 2LA and ZLB. Relay IRPP corresponds to the similarly designated relay shown and described in Letters Patent of the United States, No. 2,376,569, issued May l2, 1945, to George W. Baughman. Relay IRPP is normally held energized by a repeating relay IRP of the line relay IR and is provided with a condenser snubbing circuit by which relay IRPP is retained normally in its energized position, as shown, unless relay IR remains in its released position for a period which is greater than any interval occuring in the normal operation of the system, such as iive seconds, for example. Relay IRPP releases automatically following interruption of the communication line circuit due to a fault, and may also be released by the central office 0perator by opening the disconnect switch DB. Relay IRPP upon releasing, opens the circuit by which relay i RP is held energized by relay IR, and consequently relays IRP and IRPP will remain released. After the communication system has been restored to operation, the central oiice operator is able to reenergize relays IRP and [RPP by the transmission of a control code to the corresponding station, relay IRP being energized by the station delivery relay ID by which, as shown in the Jackel patent above referred to, the switch and signal control relays accdics LWS and 2in1-IS. areyselected. f r. operation; Relay tRPfmay also-be enereizedby the transmission of a. special, recall code without operating any of thevv control. relays, as. described. in Letters Batent of` the United States,y No. 2,396,812, issued March 19 1946,Y tov George. W.. Baug-hn-ian.

The approach locking. relay 2LAS which` has its front contact g. in: the circuit for relay IER; is normally heldenergized ina conyentional manner over a stick circuit. which extends from terminal N through its" Windingand, over its front contacta and contacts or the mechanisms ZLAG andV ZBLGVv for signals and. ZLB which` are closedwhen the. signals indica-te. stop,v to-terininal B.: at the normal contact b of. relay ZLHS.. Relay ZLAS has: two pick;v upy circuits, one including a back contacte of. a` repeater relay ITP ot the track relay Ii'IR, which isclosedwhen s ignal.2LA or ZLBis put to step' automatically byl atrain, at which time relay ZLHS- is.restored.to`, normal to closefits contact b, by the energization. ofits lower winding over back con-tact c. of relay ITP'. The. other pick up circuit for relay ZLAS. is governed. by a time element. relay ZTER. which is energized over back: contact a of. relay 2LAS Whenever signal 2LA or ZLB isput manually to stop.. and closes its.v contact a; to pick 'up' relay Z-LAS after al predetermined time interval such as; four minutes.. It;will be seen that relay ZLAS is released when signal ELA or 2LB stands at clear and` does not, p iclr` up immediately upon the return` of the signal to stop unless thisis due to the passa-gel of a train. Accordingly,` if. relay #RPP releases when one of` the signals has been. cleared; for an approaching train, relay IER. will notbecomeenergiized until the train enters section I.T to put the signal'v to stop and to pickup relay ZRAS. It;v follows that when a signal has been -cleared by remotey control for an. approaching train itA isA maintained at clear following the release oi relay IRB?, ever-1. though the train has not reached the point at whichy the approach` control is effective, Il'the train is approaching the usual distant signal inthe, rear of the manually cleared signal, thisdistant signal continues to display its proceed indication and the train is not. required to reduce its speed Furthermore, if the route` established. bythe operator is over the switch IjW init-s; reverse position,` the switch is maintained reversed until the train hastpassed over the switch.A

When relay LER. becomes. energized, it completes a stick circuit `which includes its front contact a.. and the backcontact, d of relay IRPP, so that. it remains energized untilrelay IRPP is picked up by the reception of a cede.- at the station in question.

Under `normal conditions, the emergency relay IER occupies its released positionk in which its contacts connect the windings of the control relays IW S and ZLHS. to; the terminals of the station coding4 unit provided for the; code control of'these relays, and the control relays therefore are controllable by levers ISW and ZSG as described in the Jackel patent.

The, operation of the: apparatus of my invention will. now be described. underl dilerent assumed'-conditionalstarting first with the assumption that the emergency relay IERv becomes Venergizedwhen the signaling'system is in itsnormally inactive condition, as shown, with the signals atstop. Y

When the supply. of. energy-to. the.. Winding; of relay IRPP-iS;ci1t;0fE,. the; relay" Willi release: ailier! a time interval. Relay 2LAS is picked up at this time since signals and'- ZLB- are-at stonand relay 2l'LI-IS is in its normal' position, 'and consequently relay I mit pick-s; up, and its front corrtact a vestablishes' its stickl circuit so that 'IER continues to be energized as long as relay IRPP' remains. released"- When relay IER picks up, its contacts b andc transfer the circuits for the switch control relay LW'S from the coding unit terminals 9 andl II, to. contact a of the local control relay IROC. Additionally,y the front contact d of relay 'IER establishes a connection between the upper winding of relay IKOC and theV left-hand contact of lever IKO lever is normally' biased tc a center positiomirom which it maybe operated to a lett-hand or. rightehand' position, designated bythe 'reference characters N and R, respectively. It will be. understood that other types of' circuit controllersv such as 'push buttons may be usedin place, of lever IKO if desired.

It will be. seen from vthe drawing that when relay IER. releases, relay IKOC'is operated to its normal position over a circuit which includes its upper winding andbacl; contact dof relay IER. Rel-ay IKOC. is oithemagnetic stick type, and its contacts stay in the. position to which they were last. operated, whenthe. relay is deenergize'd, so that when relay IgER. picks. up. the contacts of relay IKOC remainv in their normal position. With. contact. d of reljay I lll,v picked up, if the lever IKO. isoperatedltothe N position or the R position relay IKOC willbe energized in such manner as to cause, its. contacts. to move tothe normal or the reverse ppsitionin accordance with the operation of `theleyer IKO. Energy. isI supplied alternately to the upper or lower winding'of v switch. control relay lWS over circuits Whunmay be traced from. terminalB over. the normal or reverse contact, a ci, relay IKOC, front contact b or c of.' relay LER. through the upper or lower winding of the switch control relay lWS,.Qver the front con-tact, blcf relay 2LAS.and a front contact c o f relay LTP toterminal N. Contact act relay LWS supplies energy. from terminal Bi to. the

, switch machine. IWM'for operating tlievsw'itchto a position corresponding to that ofl relay I WS, as indicated diagrammatically in the drawing,

From the foregoingfitwill be seen that during the time that the emergency relay IER is picked up, the power switeh..i nachine IWM whichcperates the-track` switch LW. is under the control'of thelocal controlleyer IKO, so that the switch. IW

may be operated by; power locally to its normal or reverse positiomby operation of lever IKO by the' trainmenunder the. same traino conditions as those which mirmallyV permit its operationjby central cnice control. Furthermore, if theswitch IW stands in` its reversed position atv the time that the emergency relay. IER picks up, the switch control rel'ayIWS will be operated automatically to itsfnormal position, if tralic conditions are-.prcpentliereby causing `the'switclfi PW toA assume its.. normal position so that through train movements over the main track'mayco'ntinue` without the., necessity for stopping the -train in order, te locally restore the switch to normal.

Additionally, when, relay I'ERpicks up, itscontacts; e andy` Vdisconnect"thev upper 'winding of'l the signal control. relayr ZLHS from the codingA unit cuits whicngoyern thevv relay autcmatically. in acz/Rler 2f energizing the windings 2L`AG and ZIiBG-f their cerdance-withitralic conditions.

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nleclianisnis over circuits shown conventionally in the drawing which extend from terminals N through their windings over iront contacts a of relays INWP and IRWP respectively, and thence over the reverse contact c of relay 2LT-IS, and front contacts of the track relay ITR and one or more additional relays governed by traffic conditions in advance of section IT, to terminal B.

In the event that signal ELA has been cleared by remote control for a train moving from right to left and the release of relay IRPP occurs while signal 2LA stands at clear, relay 2LAS will be in its released position and its contact c' in the pickup circuit for relay IER Will be open, so that rclay IER will remain released and the signal will remain at clear. When the train in question accepts the signal and enters section IT, the track relay ITR and its repeater relay ITP will release. Front contact d of relay ITR will interrupt the circuit for supplying energy to the winding ZLAG for signal SLA, iront contact c of relay ITP will maintain the circuit for relay IWS open, and back contact c of relay ITP will close the circuit for restoring the relay ZLHS to normal. Relay ZLAS will then be picked up over back contact e of relay ITP, and when contact g of relay 2LAS closes, the pick-up circuit for relay IER will be completed and the relay will pick up, transferring the control of the relay ZLHS to the local control circuits, but relay IWS will not be operated until section IT is vacated, as is obvious. It will be seen therefore, that the deenergization of the relay IRPP cannot cause any signal which has been cleared to be put to stop in front of an approaching train, nor can it cause the operation of a track switch in front of an approaching train or under a train.

The operation of the apparatus under emergency conditions by approaching trains will now be described, assuming that the relay IER is picked up, relay IKOC being in its normal position, as shown.

If a train is approaching signal 2LA on the main track, moving from right to left, the current supplied from the battery ZLTB to track section 2LT will increase in value until a point is reached where relay ZLAR picks up.

When relay 2LAR picks up, a circuit is established for supplying energy of reverse polarity to the lower winding of relay 2LT-IS, which circuit may be traced from terminal B at the front contact b of relay INWP over front contadt d of relay ZLAR, over normal contact b of relay IKOC, front contact g of relay IER, through the upper Winding of relay 2LT-IS from right to left, and thence over front contact e of relay IER, normal contact c of relay IKOC, front contact e of relay ZLAR and front contact a of relay ITP to terminal N. Accordingly, the contacts of relay 2LHS will be operated from their normal to their reverse position. rPhe opening of contact b of relay ZLHS releases relay ZLAS, and the closing of the reverse contact a of relay ZLHS completes the circuit already traced for the winding ZLAG. Accordingly, it will be seen that if the switch IW is in its normal position, section IT unoccupied, and conditions in advance of section IT are proper, the approach of a train on the main track will cause the circuits to be controlled in such manner as to clear signal 2LA for the approaching train.

When the train passes signal ZLA and occupies section IT, relays ITR and ITP release. When relay ITP releases, its front contact c interrupts .Y the circuit for relay IWS, so that relay IWS .cannot be .operated with a train occupying section IT. Back contact c of relay ITP completes the circuit for the lower winding of relay 2LHS, and at the same time, front contact a of relay ITP interrupts the circuit for the upper winding of relay ZLHS, so that relay ZLHS is operated to normal. Signal 2LA is accordingly put to stop by the opening of front contact d of relay ITR in the signal circuit, and is held at stop by the opening of contact a of relay ZLHS.

When the train moving from right to left vacates section 2LT, the value of current flowing through the winding of relay 2LAR decreases to such an extent that the relay releases. When relay ZLAR is released, a circuit is established for supplying energy of normal polarity to the upper Winding of relay 2LT-IS, which circuit may be traced from terminal B at back contact e of relay 2LAR, over normal contact c of relay IKOC, over front contact e of relay IER, through the upper winding of relay ZLHS from left to right, over front contact g of relay IER, over normal contact b of relay IKOC, and over back contact d of relay ZLAR to terminal N. Thus relay 2LT-TS is supplied with energy at this time of such polarity that it is held in its normal position.

It will be seen therefore, that when signal ZLA has been clearedrby the approach of a train in section 2LT, it is restored to stop when the train vacates this section even though the train does not occupy section IT.

Assuming however, that the train continues its movement from right to left from section 2LT through section IT, when the train vacates section IT, relays iTR and ITP pick up. Contact c of relay ITP again completes the circuit for the switch control relay IWS, and opens the restoring circuit of relay 2LHS. Relay 2LT-IS is retained in its normal position by energy supplied over the circuit traced above, including the back contacts d and e of relay ZLAR.

From the foregoing it will be seen that a train approaching signal ZLA on the main track, when the communication system is disabled, will automatically clear the signal ZLA in advance of the train so that the train movement may be continued.

Assuming now that an approaching train is on the siding section 4LBT and that the train crew have authority to move the train from right to left from the siding to the main track, after stopping at signal ZLB one of the trainmen will operate the manual control lever IKO momentarily to its R position. When lever IKO is reversed, a circuit is established for reversing the contacts of relay IKOC, and as a result, relay IWS assumes its reverse position, releasing relay INWP and causing the switch movement IWM to operate switch IW to its reversed position, and then the reverse switch repeater relay IRWP becomes energized. Since the train is occupying section ZLBT, the series approach relay ZLBAR is picked up, consequently when relay IRW'P picks up a circuit is established for reversing the signal control relay ZLHS, which extends from terminal B at front contact c of the relay ZLBAR, front contact e of relay IRWP, reverse contact b of relay IKOC, front contact g of relay IER, through the upper winding of relay ZLHS from right to left, thence over front contact e of relay IER, reverse contact c of relay IKOC, front contact g of relay IRWP, and front contact a of relay ITP to terminal N. As a result, the contacts of relay 2LT-IS are operated to their reverse position. Relay ZLAS releases and maylave the siding. 'When the train passes signalsZkLB and enters section IT, the relaysl I TR i and 'ITP release, restoring the signal control 2LHS toits normal position, opening the signal control'circuit at front contact d of relayITR, fand also opening the circuit for-'controlling the switch control relay I WS, so that the switch IW \'eann`ot be operateduntil the-train vacates Asect-ion IT. vIf an approachingtrainnow enters the 4maintrack section 2LT, signal-2BA willfnot'clear automatically as hereinbefore described, due to the fact that the switch IW and its control relays stand reverse.

In this case the switch IW may be restored to its normal position and signal 2LA cleared by the operation of the lever IKO. When the lever IKO is placed in the N position, the contacts of relay IKOC are restored to normal and if the locking conditions permit its operation, the switch control relay IWS operates its contacts to its normal position, the operation of its contact b causing relay I RWP to release, and the operation of its contact a supplying energy to the switch machine IWM to restore switch IW to normal, whereupon relay INWP becomes energized.

Since relay 2LAR is now energized due to the presence of the train in section 2LT, and since the left-hand contacts of relay IKOC are closed, relay ZLHS is operated to reverse as soon as the switch assumes its normal position, due to the closing of contact b in the circuit for relay 2Ll-IS which includes the front contacts d and e of relay ZLAR, and relay 2LHS then releases relay IRAS and clears signal 2LA in the manner already described.

From the foregoing, it will be seen that during the time that the emergency relay IER. is picked up, the switch IW is free to be operated by the manual control lever IKO under proper traiiic conditions to set up a route for a train standing either on the side track or the main track,A and that when the switch is properly positioned, the presence of a train in the approach section will operate the circuits to clear the signal to enable the train to move over the switch.

Although I have herein shown and described only one form of my invention, it is to be understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my`V invention, ywhat I claim is:

1. In a centralized traffic control system for a stretch of railway track including a track section having a track relay and an approach section having an approach relay each adapted to :detect the presence of a train in its section, said system including a signal for governing the movement of traffic from said approach section into said track section, together with a signal control relay for governing the clearing of said signal, a communication circuit extending to a control oiiice over which said signal control relay is manually controllable from said oiiice, said system also including means controlled by. said track relay for restoring the signal control relay automatically to normal when said track section is occupied by a train, the combination of the foregoing with an emergency relay, means for operating said emergency relay effective when said 'relayfnieanscontrolled by 'said em'ergericyY "in its operated' position for' rendering said sig 'relay responsive to the operation of said apprqach communication circuit is disabled SQ as to prevent the manual control of isaidsig'iijal control relay to effect the clearing: of Asaid' signal "auto- `matically upon the approach of a train, "and means' for 'delaying the operation' of fthe 'e'rrifer gency relay if said'communication circuit becomes disabled when the signal has 'been 'clearedb'y 'manual control, until the signal control relay has been restored automatically to normal by "the yrelease of said track relay, s y b 2. In 'a centralized traffic control @system-fr a sie@ faire @fascisme ia deeper including a power voperated track 4switch and equipped with signals for governing the movement of traffic over the routes established by the switch in its respective normal and reverse positions, said system including a track relay for detecting the presence of a train in said section and switch indication means for selecting one signal or the other for clearing in accordance with the position of the switch, said system also including a switch control relay for operating the track switch and a signal control relay for clearing the selected signal and having a communication circuit extending to a control oice over which said control relays are manually controllable from said oflice, the combination with the foregoing of an emergency relay, means for operating said emergency relay eiective when said communication circuit is disabled so as to prevent the manual control of said control relays, a local switch lever at the switch location, means controlled by said emergency relay in its operated position for rendering said switch control relay responsive to the operation of said switch lever and for preparing local operating circuits for said signal control relay, and means controlled by said switch lever for completing one of said prepared circuits to elfect the clearing of the signal for the route selected by the operation of said switch lever.

3. A centralized traflic control system of the type recited in claim 2, in which the means for governing the switch control relay by the local lever comprises a local relay of the stay-whereput type, and in which the local operating circuits prepared for the signal control relay by the emergency relay are completed over contacts of the local control relay only when the switch assumes a position corresponding to that of said contacts.

4. A centralized trafiic control system of the type recited in claim 2, in 'which the signals govern movements over the switch in the trailing direction and the tracks adjoining the detector section on the trailing side are provided with approach relays for detecting the presence of trains approaching said signals, and in which the local operating circuits for the signal control relay are completed by the approach relay only when there is a train in approach to the signal selected by the local control relay.

5. In a centralized traiiic control system f or the control of a power operated track switch located in a detector track section and having signals for governing the movement of traiiic through said section, said system including a track relay for said section, an approach locking relay controlled by the signals in their stop posi- 'Y tions and a switch control relay for operating the switch, said switch control relay Abeing operable only when said track and approach locking relays are energized, said system also including'a communication circuit extending to a control oiice control relay, a switch lever at the switch loca- 5 tion, means for operating said emergency relay effective when said communication circuit is disabled so as to prevent the control of said switch control relay from said oflice, means controlled by said emergency relay in its operated position for rendering said switch control relay responsive to the operation of said local control relay, and for rendering said local control relay operable to normal or reverse in response to the operation of said switch lever, and means controlled 15 12 Y by said emergency relay for maintaining said local relay in its normal position when said emergency relay is in its normal position.

HARRY C. VAN TASSEL.

References Cited in the l'lle of this patent UNITED STATES PATENTS Number Name Date 10 1,805,531 Stoltz May 19, 1931 2,153,518 Hailes Apr. 4, 1939 2,430,291 Hays Nov. 4, 1947 2,520,838` Hays Aug. 29, 1950 2,605,391 Preston July 29, 1952 

